One of the earliest metal connectors provided for the building industry for connecting two wood members was the structural strap tie. There is no known recorded earliest use of metal straps. Smelted iron has been found dating from 2700 B C at Tell Chagar Bazar (northern Syria) but metal was scarce and did not come into common use until about 1000 B C. We can assume that metal straps have been in relatively common use for connecting two timber members from about the first millennium B C until the present.
Even though metal straps have been in common use for nearly three thousand years and metal has been a commodity which has always required careful design to conserve its usage, even today straps are formed in rectangular configurations with straight edges; a form identical to earliest times. An example of a metal strap of the traditional rectangular shape with straight edges is shown in the catalog of one of the largest metal connector manufacturers. (See Prior Art Simpson Catalog 1981, Page 23).
No attempt had been made to change the rectangular strap except to change the nail patterns to meet local and national building codes. The spacing between holes is dictated by building codes for each typical nail size. This has resulted in a slightly improved strap as illustrated by the staggered nail design found in the MST type of strap found in the 1981 Simpson catalog, supra.
A further building code and practical requirement is that the edge distance (in the case of steel) between any nail hole and the nearest edge of the metal shall be not less than one and one-half times the dimension from the center of the hole to the edge of the metal.
Although many have known that rectangular metal straps with straight edges used as a structural tension member had an excess net section which was wasteful of metal; the design remained unchanged for lack of a more efficient design and cost effective method of producing such straps.